First pass at uniformed types, specs and docs

- spec public functions (skipping controllers, views, live views and
components)
- use types instead of explanations in docs
- remove redundant docs
- fix typos

lib/music_library/barcode_scan/result.ex

@@ -1,6 +1,14 @@
 defmodule MusicLibrary.BarcodeScan.Result do
   defstruct [:status, :number, :record_id, :release]
 
+  @type t :: %__MODULE__{
+          status: :new | :wishlisted | :collected | :not_found,
+          number: String.t(),
+          record_id: String.t() | nil,
+          release: map() | nil
+        }
+
+  @spec new(String.t(), map()) :: t()
   def new(number, release) do
     %__MODULE__{
       number: number,
@@ -9,6 +17,7 @@ defmodule MusicLibrary.BarcodeScan.Result do
     }
   end
 
+  @spec wishlisted(String.t(), String.t(), map()) :: t()
   def wishlisted(number, record_id, release) do
     %__MODULE__{
       number: number,
@@ -18,6 +27,7 @@ defmodule MusicLibrary.BarcodeScan.Result do
     }
   end
 
+  @spec collected(String.t(), String.t(), map()) :: t()
   def collected(number, record_id, release) do
     %__MODULE__{
       number: number,
@@ -27,6 +37,7 @@ defmodule MusicLibrary.BarcodeScan.Result do
     }
   end
 
+  @spec not_found(String.t()) :: t()
   def not_found(number) do
     %__MODULE__{
       number: number,